The planar reflection technique described previously can be extended to objects that tend to scatter a significant fraction of the light that they reflect or transmit. Objects viewed through a translucent surface become more difficult to see the further they are from the reflecting or transmitting surface, as a smaller percentage of unscattered light is available for the the viewer. To simulate this effect, fogging can be enabled, where fogging is zero at the translucent surface, and increases as a linear function of distance from that surface. Reflection and transmission can be handled separately, as a two pass sequence, setting the fog equations appropriately for each pass. Linear fogging is a good approximation of this effect, but a non-linear fogging technique, perhaps using a texture map and a texgen function perpendicular to the translucent surface, could be used to increase realism.
Realism can be further enhanced by applying multiple shearing transforms to objects as function of their perpendicular distance to the translucent surface, and accumulating the results. This helps simulate the scattering of light by the translucent surface. This technique is the same one used to generate depth of field effects, except the effect is generally stronger.